Non-volatile memory devices that retain stored data in the absence of power are pervasively used in many electronic products. Unfortunately, many non-volatile memory devices have limitations that make them unsuitable for use as primary storage for these products including higher cost and lower performance when compared to volatile memory devices such as dynamic random access memory (DRAM). Examples of non-volatile memory devices include read-only memory (ROM), flash memory, ferroelectric random access memory (FRAM), resistive random access memory (RRAM), phase change memory, and the like.
RRAM, and filamentary RRAM in particular, have recently gained development momentum. A challenge to RRAM device commercialization is high write current requirements resulting from long bit lines having high capacitance. When the RRAM cell switches, capacitive surge currents from long bit lines discharge through the cell making the filament wider. Relatively high write currents are needed to break the wider filament. For example, if the capacitance of a bit line is 0.1 pF and the RRAM switches in 1 ns at 2V, the surge current is given by:I=C×dv/dt=0.1×2V/1 ns=200 uA
This 200 uA current during a SET operation often requires a similar 200 uA current during a RESET operation, which, in turn, results in a power hungry RRAM device that reduces battery life. Many electronic products, however, require extended battery life. A need exists, therefore, for an improved reduced current memory device.